When should you puncuate with italics or underlining?

You're asking about italics and underlining, which are used for emphasis and to highlight specific words or phrases within a sentence. Here's a breakdown:

Italics:

* Titles of Books, Plays, Films, and Long Musical Compositions: *Pride and Prejudice*, *Hamlet*, *The Godfather*, *Symphony No. 5 in C Minor*

* Foreign Words and Phrases: *ad hoc*, *coup d'état*, *Schadenfreude*

* Words or Phrases Emphasized for Effect: "I *really* need to finish this project today."

* Scientific Names of Species: *Homo sapiens*, *Canis lupus*

* Ships, Aircraft, and Spacecraft: *USS Enterprise*, *Boeing 747*, *Apollo 11*

Underlining:

* Pre-Computer Age: Underlining was commonly used in place of italics for emphasis or titles when typewriters or similar technology didn't have italics capabilities.

* Handwritten Text: Underlining can be used to emphasize words in handwritten text, though italics are more common in digital environments.

* Specific Styles or Guides: Some style guides, such as APA or Chicago, might have specific guidelines on when to use underlining.

Important Notes:

* Consistency: Choose either italics or underlining and stick with it throughout your writing. Don't mix them.

* Overuse: Avoid overuse of italics or underlining. Too much emphasis can make your writing seem forced or unprofessional.

In the digital age, italics are generally preferred over underlining for the reasons mentioned above.